Timestamping Data Packets with Forward Error Correction
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Solution Overview
Problem
Timestamping of data packets in network communications is prone to inaccuracies due to factors like packet scrambling and transfer between domains with asynchronous clocks, leading to lower precision in determining the time of packet arrival.
Innovation Solution
The implementation of a compute device with a network interface controller that inserts alignment markers, detects trigger patterns, and employs forward error correction algorithms to ensure accurate timestamping by encoding and decoding data packets, thereby minimizing the impact of asynchronous clock operations and packet scrambling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If packet scrambling is applied for error protection, then reliability is improved, but timestamping precision deteriorates because the packet pattern becomes unrecognized
Solution Approach 1:
The patent applies preliminary action by performing timestamping before the packet scrambling operation. The network interface controller captures the timestamp at the point where the packet pattern is still recognizable, prior to scrambling modifies the packet bits. This timing ensures that the timestamp reflects the actual arrival time accurately, while the scrambling is applied subsequently for error protection without affecting the timestamp precision.
2Reliability
If forward error correction encoding is applied to data packets, then reliability is improved, but device complexity increases due to additional encoding and decoding operations
Solution Approach 1:
The patent introduces an intermediary approach by having the network interface controller handle the FEC encoding and decoding operations as a mediator between the packet data and the timestamping function. The NIC performs these operations in a controlled manner, isolating the complexity from the core timestamping mechanism while ensuring reliable data transmission. This allows the system to achieve error correction without proportionally increasing overall device complexity.
3Reliability
If timestamping is performed after packet manipulation operations, then reliability of packet processing is improved, but measurement precision of arrival time deteriorates
Solution Approach 1:
The patent applies preliminary action by performing the timestamping operation before packet manipulation such as scrambling and FEC encoding. The network interface controller captures the timestamp at the point of packet arrival when the packet pattern is still recognizable, and only afterward do the manipulation operations are applied. This timing sequence ensures that the timestamp accurately reflects the arrival time while still allowing reliable packet processing to occur subsequently.
Data Source
AI summary
Technologies for timestamping data packets with forward error correction is disclosed. Alignment markers may be inserted in a data stream in order to assist with synchronization on the receiving end. After insertion of the alignment markers, a start of frame delimiter or other trigger may be detected, triggering a timestamp corresponding to the start of frame delimiter or other trigger. The data and the timestamp are sent to a remote compute device, which may timestamp the data before removing the alignment markers. With this approach, insertion of the alignment markers does not lead to a deviation in the timestamp of the sending compute device or the receiving compute device.